Typically, sulfuric acid esters of amino alcohols including ethanolamines have been produced by reacting hydroxy aliphatic or cyclic alkanolamines with concentrated sulfuric acid or sulfur trioxide. Water is formed in the reaction with sulfuric acid, and, in order to drive the reaction to completion, the water must be removed. Representative patents which illustrate the formation of sulfuric acid esters of amino alcohols by reaction of amino alcohols with sulfuric acid or sulfur trioxide and illustrate techniques for effecting removal of the water during the reaction for the amino aliphatic and cyclic hydrogen sulfate product are as follows:
U.S. Pat. No. 2,264,759 discloses the production of amino aliphatic hydrogen sulfates including aminoethyl hydrogen sulfate by reacting a hydroxy aliphatic amine with concentrated sulfuric acid in the presence of an organic solvent. Various solvents, e.g., hydrocarbons and chlorinated aromatic hydrocarbon solvents are added to the process to enhance the removal of water formed during the reaction. The addition of solvent to the reaction medium permitted distillation of water from the reaction medium at atmospheric pressure. Hydrogen sulfate salts of ethanolamine, triethanolamine, propanolamine and cyclohexylamine are shown.
U.S. Pat. No. 3,194,826 discloses a process for producing 2-aminoalkanol esters of sulfuric acid, particularly 2-aminoethyl hydrogen sulfate, by reacting monoethanolamine with sulfuric acid at temperatures from about 120.degree.-200.degree. C. Instead of removing all of the water from the reaction mixture prior to purification of the product some is retained to permit controlled crystallization.
U.S. Pat. No. 3,133,950 discloses a process for reacting an alkanolamine with sulfuric acid in the presence of a small amount of a cationic surface active agent. In an effort to force the reaction to completion, the reaction is carried out in the presence of an inert volatile solvent which is capable of forming an azeotrope with water. Representative cationic surface active agents include long chain quaternary ammonium compounds, fatty acid diamine condensates and fatty acid carbamides.
U.S. Pat. Nos. 4,330,480; 3,153,079 and 3,194,826 show variations on the above themes in the manufacture of aminoalkyl esters of sulfuric acid.
U.S. Pat. Nos. 3,169,143, 3,763,208 and 3,337,633 disclose the preparation of sulfuric acid esters of aminoalkanols, particularly 2-aminoethyl esters of sulfuric acid, by reacting an alkanolamine with sulfur trioxide. The '333 patent shows the preparation of sulfuric acid esters of ethoxy linear saturated secondary alcohols by reacting an ethoxy substituted alcohol with sulfamic acid.